ABSTRACT

Whereas for the truss, the member stiffness matrix was a 4 X 4, the beam element member stiffness matrix becomes a 6 X 6. Because of this extra complexity, the derivation is done in two steps: (i) the stiffness matrix is found relative to the member's own or local coordinate system; (ii) it is then 'transformed' into global coordinates relative to the structure's coordinate system.